Chicago/Turabian - Citation Style
The current version of the Chicago style is published in The Chicago Manual of Style, 16th ed. (Chicago: U of Chicago P, 2010). The style rules are subject to change with every new edition, so always make sure you are working with the most up-to-date version.
The Chicago Manual of Style Online provides detailed information on the basics of Chicago style and updates to the current version.
More information can be found in Kate L. Turabian's A Manual for Writers of Research Papers, Theses, and Dissertations, 8th ed.
Purdue Online Writing Lab Chicago Formatting and Style Guide
Provides in-depth information on how to use Chicago style, including many examples.